This invention relates to digital television systems and services and particularly to signal processing methods and apparatus for use with such systems and services.
Digital television is an emerging technology, which is becoming increasingly popular with the public. One of the more interesting aspects is the introduction of so-called xe2x80x9chigh-definition televisionxe2x80x9d (HDTV), the broadcasting of which was recently approved by the United States Federal Communications Commission. HDTV will provide television images of much higher quality and definition than is provided by preexisting xe2x80x9cconventional definitionxe2x80x9d television systems.
Another highly important aspect of digital television is the providing of related services, such as video-on-demand programming, pay-per-view movies and sporting events, interactive video games, home shopping capabilities, high-speed Internet access and the like. The home television set is fast becoming the predominate information and services dispensing medium of the future.
As is known, television services are presently communicated by land-based radio-type broadcast transmissions, cable network transmissions and space satellite transmissions. In order to limit reception to paid subscribers, it is common practice for cable and satellite providers to scramble their transmissions and to require their customers to use a special set-top control box to unscramble the received signals. Such scrambling and set-top box techniques are also desired by providers of related services. The problem to date is that each provider has developed its own unique and proprietary set-top control box. Thus, to receive and use signals from multiple providers requires the use of multiple set-top control boxes. This is not the best situation and, in order to overcome the problem, the U.S. Federal Communications Commission is encouraging a so-called xe2x80x9copenxe2x80x9d set-top box approach for providing a universal set-top box capable of receiving and handling content from multiple providers. Unfortunately, this is not an easy thing to do and at the same time provide the security control features needed to protect the various service providers from loss of services to unauthorized users.
As the demand for television related services increases, the communications requirements between the user""s television receiver equipment and the central broadcasting station becomes more and more complex. More communications channels are needed for passing the necessary television signals, information signals and control signals from the central broadcasting station to the end user. This problem is further complicated by the need for the security control features to prevent unauthorized use of services. More control signals and security related information need to be communicated. Thus, there is an increasing need for transmitting more and more data and information for different uses and purposes, some in a continuous manner and some in an occasional or intermittent manner. Thus, there is a need for improved methods for transmitting information for different applications and end uses over a limited number of signal channels. And there is a corresponding need to provide better ways of receiving and distributing the information to the different end uses at the receiving end of the system.
The present invention provides a new and improved digital filtering mechanism for separating signal segments intended for different applications and end uses. This filtering mechanism includes input circuitry for receiving a digital signal stream comprised of digital data bytes. A digital pattern selection mechanism provides a way of pre-filtering data bytes according to their relative position. The programmable filtering mechanism provides a way of filtering data bytes according to their successive values. The present invention further allows distributing the total amount of reference data bytes to be matched, into a programmable number of parallel independent filtering sub-mechanisms. The more filtering sub-mechanisms are activated, the shortest their reference sequence is. While one of the sub filtering mechanism is matching its reference sequence, it provides a match indication signal. A data extraction mechanism is responsive to the match indication signal for transferring a corresponding group of received data bytes to an end use location assigned to the end use identified by the digital signal pattern, which produced the match.
There is also described a private recording feature for making and using a private copy of the received signals. This is accomplished by scrambling the signals in accordance with a private cipher key before they are recorded and thereafter descrambling the recorded signals in accordance with this same private cipher key when they are played back.